Naoya Inoue plans to come up with what he calls a "reserve tank" by the time he gets into the ring with fellow two-belt world super-bantamweight champion Marlon Tapales on 26 December in Tokyo.

After concluding another round of strength and conditioning training and intense sparring, Inoue said the severity of his preparation for the unification showdown heats up further in the coming weeks.

"We are working on building up the stamina so I could still fight on at a high level even when fatigue sets in," Inoue, nicknamed "Monster," said in Japanese.

The undefeated Inoue holds the World Boxing Council and World Boxing Organization straps while Tapales owns the World Boxing Association and International Boxing Federation belts.

Their scheduled 12-rounder will be staged at the Ariake Arena with four judges from neutral countries representing each of the boxing bodies working the much-awaited match.

Like Inoue, Tapales is also in the thick of training in Baguio City where he kicked off his camp after relocating it from the United States last week.

He began sparring a couple of days ago and took the day off Sunday to attend a church service and go on horseback-riding, a popular Baguio activity.